Lightning-arrester.



Q. A. BRACKETT.

LIGHTNING ARRESTI-IR.

APPLICATION FILED APII.29. I9I5.

Patented Jan. 14,1919.

INVENTOR if l. 5mn/fa# WITNESSES: ffm/4M ATTORNEY UNITED sTATEs PATENT oEEIoE.

QUINCY A. BRACKETT, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN'- SYLVANIA.

. To all whom t may concern.'

QUiNcY A. BRAGKETT, v

Be it known that I, a citizen of the United States, and a resident of Pittsburgh, in the county' of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in LightningArresters, of which the followingisa specification.

y invention relates to electrical protec tive devices, and it has special reference to devices inserted in electrical circuits to pro tect the apparatus associated therewith from high-frequency surges or impulses.

More particularly, my invention relates to lightning arresters of the choke-coil type in which the inductive effects arising there from, when subjected to the flow of currents -of normal or commercial. frequencies are negligible, but, when subjected to the flow of high-frequency currents, such as obtain in lightning disturbances, are considerable and, consequently, effective in precluding the discharge of such current to the electrical aplse paratus connected in circuit.

It is a common practice to insert ordinary choke coils comprising a relatively small number of turns, in circuit with line conductors in order to protect the electrical apparatus from the efects of high-frequency currents arising on the transnnssion line.l

Choke. coils of this character reflect a portion of the high-frequency currents back upon the line, permitting portions only of the disturbances to lilter through to the electrical apparatus. However, when severe disturbances occur on the transmission lines,

a considerable quantity of these high-frequency currents may be permitted to flow` through choke coils of the ordinary type to the electricalapparatus, `In these instances, the strains arising from the admission of these filtered higli-frei'piency currents may be sufficient to'puncture the-insulation employed in theelectrical apparatus.

Heretofore, the inductive effect resulting from such choke coils, which have no magnetizable core members, has been limited' to relatively small values, ybecause' the impedance offered to the flow of. currents of normal or commercial frequenciesV must be maintained low .for obvious reasons. As a -result of liinitin the numberfof turns of oke coils, they., are-frethese lo;.fdinary c Specification of Letters Patent.

LIGHTNING-ARRESTER.

Patented Jan.. i4, 1919.

Application lc. April 29, 1915. Serial No. 24,744.

quently ineffective in suppressing high-frequency disturbances.

One object of my invention is to provide a lightning arrester of the choke-coil type which will offer very little or negligible impedance to the iiow of currentsof normal`or commercial frequencies but which will offer high impedance to the flow of high-frequency currents, such as obtain in lightning disturbances andthe like.

For a better understanding of the nature' and scope of my invention, reference may be had to the following description and the accompanying drawing in WhiclrFigure l is a diagrammatic view of a lightning arrester constructed in accordance with my invention; Fig. 2 is a diagramn'iatic viewfof a modified form of the device shown in Fig. 1, and Figs. 3, el and 5 are diagrammatic views of modified forms' of the devices shown in Figs. l and 2. v

Referring particularly to Fig. 1, a line conductor l is connected in series relationship with a divided circuit The divided circuit 2 comprises a coil 3 and a coil l which tively large number of turns and,rwhen energized alone, is of high inductance. However, the said coils are oppositely Wound. and so disposed on the core member 7 that the iuxes generated by currents of normal frequencies flowing therethrough are oppositely directed. Again, the coils 3 and 4 are composed of the same number of turns and, consequently the value of the resultant mag- .netic flux flowing through the core member 7, under normal conditions, is substantially zero. Thereforeythe.inductance offered' to the flow of the line currents along the conductor 1 is negligible. However, when high-frequency `disturbances of short wave lengths tend to flow along. the conductor-1, thekiinpedance offered by the coils 3 and 4 is ,very great. Therefore, the disturbances are reiected back upon the` linehandthe On the other hand, the period of this hysteretic lag is of small import when the currents iiowing through lhe coils 3 and 4 are of relatively low freq ieiiicies, such as are utilized in commercial"power circuits.

lVhile I have shown and describedseveral embodiments of myI invention, it Will be apparent to those skilled in the art that many modifications may be made Without departin from the spirit andscope of the appende claims.

I claim as my invention 1. A protective device comprising a magnetizable core member forming a' closed mag. netic circuit' of high hjsteretic lag and having a plurality of core legs, coils severally embracing the Ylegs of said core member, said coils being oppositely wound and connected in parallel relationship with each other and in series relationship with a line conductor.

2. A protective device comprising a magnetizable core member forming a closed magnetic circuit and being composed of material having a high hysteretic lag, coils embracing the several'llegs of said corememberv and being oppositely Wound and connected in y parallel relationship ivitheach other and in series rel'atioiishipu'ith a line conductor whereby the coils Will magnetically neutralize each other when low-frequency currents lioW therethrough but which Will act as independent reactive elements When highfrequency currents flow therethrough.

3. The' combination with a line conductor subject, at times, to the fioivbf low-fiequency currents and, at other times. to the flow of higl -frequency currents, of a fre! quency-selective inductive devi-,ce inserted therein, said device comprising a plurality of current-carrying conductors connected in parallel relation and means for closelv magnetically coupling said conductors with loir# frequency currents and for loosely magnetically coupling said paths with high-frequency currents. 'i

4. The combination with a line conductor subject, at times. to the. flow of. louffrequency currents and, at other times, to he iiow of high-frequency currents, of aj yfrequency-selective inductive device inserted therein, said device comprising` a plurality of current-carrying conductors connected in parallel relation and each arranged to carry a portion of the line current. and a magnetic core member inductivelv interlinking said conductors. the dimensions and magnetic properties of said core member being such that it affords a relatively close coupling between said conductors at low frequency and a relatively loose coupling with high frequency.

5. The combination with a line conductoi.1 subject, at times, to the flow of low-frequency currents and, at other times, to the 'parallel relation and each arranged to carry a portion of the line current. and a magnetic core'member inductively linking said conductors, the algebraic sum of the magnetomotive forces developed within said core member by said conductors being subst-.intially Zero and the dimensions and magnetic properties of said core member being'such that the hysteretic lag therein on high-frequency currents renders the magnetic coupling of said conductors less effective than with low-frequency currents.

6. The combination with a line conductor subject, fat times, to the flow of low-fre-A quency currents and, at other times. to the flow of high-frequency currents, of a frefluency-selective inductive device inserted therein, said device comprising means for developing' a plurality of inagnetomotive forces from said line current in a common core member, the. algebraic sum of said magnetomotive forces, as combined, being substantially zero vand the 'dimensions and magnetic properties of said core member being such that the coupling action thereof on the seats of magnetomotive force is looser -on high-frequency currents than on low-frequency currents.

7. The combination with two electric conductors subject, at times, to-the floW of loW- frequency currents, and, at times. to the iioiv of high-frequency currents, the relative directions of current flow between said conductors being the same with both conditions of frequency, of means for magnetically coupling said conductors. the algebraic 'sum of the magnetomotive forces of said conductors. as combined. being substantially zero and said coupling means affording a closer cou-'- pling with low-frequency currents than with, high-frequency currents.

R. The combination with two electric lconductors subject, at times, to the flow of lowfi'equency currents, and. at times, to the flow of high-frequency currents, the relative directions of current flow between said conductors being the same with both conditions of frequency. of a core member, and means *for developing a magnetoinotive force in said core member from the currents of'each of said conductors, respectively, the algebraic sum of s .d magnetomotive forces as combined being substantially Zero, and the dimensions and magnetic properties of said core member being such that an appreciably looser coupling is aiforded with high-frequency currents than with low-frequency currents.

9. The combination With two electric coni euirehl;e the ifele'tive di- J of flow between eters being me 5eme with beth conditions ei frequency, ei-S Coils ineeiesl in each of .Seid eondaieors, ieejpeetivey, and embracing @ommen Coffe member, lle algebraic sum the iimghetgmotive forcee of seid coils, ne mleinedr ui Sem e member, being euhetentielly zere und themeteriel' of seid weie-ee core member having e pronounced hysteretie 10 subscribed my neme this 23rd dey of April 15 QUI'NGY A., BRACKETT egeee ef palmari: may eebteim im' ive Gente each, by addressing' the Commissioner of Patente,

'- Weehngee, )3. E. 

